The present invention relates to a rotary machining apparatus for polishing a surface such as a semiconductor substrate and, more particularly to a rotary machining apparatus having a function to remove asperities on a surface of a polishing tool for polishing a semiconductor substrate.
A semiconductor manufacturing process is composed, of various kinds of processing processes. As the needs of higher speed processing and higher density for semiconductor devices are growing in recent years, the trend of the circuit elements is accelerated to move toward multilayered structures. The trend of the multilayered structure of the circuit elements causes a problem in that a step is formed on a boundary between a region having a circuit element formed and a region having no circuit element on a semiconductor substrate, and the step is increased higher every time the layer is overlaid. As a result, when mask exposure is performed in the photo-lithography process, there are some cases that the depth of focus exceeds or etching becomes difficult to be performed in the upper layer side.
In order to solve the above-mentioned problems, technologies to flatten the surface of semiconductor substrate. As the flattening technology for the purpose known is a chemical mechanical polishing (CMP) technology in which an abrasive (slurry), which suspends abrasive particles such as alumina or silica particles in hydrogen peroxide or the like, is let flow on a soft or viscoelastic polishing pad, the polishing pad is rotated, and a silicon wafer or the like is pushed against the polishing pad to polish the surface of the wafer.
However, the technology has problems that the surface can not sufficiently flattened depending on the kind of pattern or the condition of step because the soft or viscoelastic polishing pad is used, and that the consumable cost becomes large because the slurry liquid is always let flow.
A polishing apparatus is disclosed in W097/10613. The polishing apparatus solves the above-mentioned problems using a grinder composed of grinding particles and a binding resin for binding the grinding particles.
A polishing tool used for flattening a semiconductor substrate is required to have higher flatness as it becomes harder. The reason is that in comparing with a soft polishing tool, existence of asperities on the polishing surface of the hard polishing tool unevenly, not flat, polishes a semiconductor substrate to be polished, or on the contrary the polishing tool is sometimes broken by applying a concentrated pressure to a specified portion of the polishing tool during polishing.
A technology to form a surface of a polishing tool into an arbitrary shape is disclosed in Japanese Patent Application Laid-Open No.7-9325. The patent discloses a moving mechanism which comprises a tool for forming a surface of a polishing tool into an arbitrary shape, and moves the tool toward arbitrary directions.
Such a tool is likely to be broken when the tool is pushed against a polishing tool with a strong force, or when the polishing tool is polished in excessively large depth. Particularly, this tendency becomes more pronounced as the polishing tool is harder. Therefore, polishing (configuring) is necessary to be started by bringing the tool close to a position not to damage the polishing tool. However, the polishing apparatus disclosed in Japanese Patent Application Laid-Open No. 7-9325 is not sufficient in this point.
An object of the present invention is to provide a polishing apparatus which is capable of configuring a surface of a polishing tool without damaging the polishing tool. Further, another object of the present invention is to provide a polishing apparatus which is capable of reducing process time for polishing the surface of the polishing tool.
In order to solve the above-mentioned problem, the present invention provide a rotary machining apparatus comprising a polishing tool for polishing a sample; a rotary disk for holding the polishing tool; a tool for configuring a surface of the polishing tool; and a position adjusting mechanism for adjusting a gap between the tool and the polishing tool, which comprises a rotating mechanism for rotating the tool; and a sensor for sensing a change in the rotation of the rotating mechanism, a height at starting to configure the polishing tool using the tool being determined based on the change in the rotation obtained by the sensor.
By constructing as described above, contact between the tool and the polishing tool is sensed from a change in rotation of the tool, and the height at starting to configure the polishing tool using the tool can be determined by the contact point.
The other construction in accordance with the present invention will be further described later in the section of DESCRIPTION OF THE PREFERRED EMBODIMENTS.